Brad DeLong catches Niall Ferguson
making another whoopsie. And while chasing NF isn’t worth the effort
for its own sake, I think there is a broader lesson here: namely, the
importance of knowing what you don’t know.

My own unpleasantness with Ferguson began when he tried to weigh in on monetary versus fiscal policy without understanding basic macroeconomics. Later, he tried to critique official inflation numbers
without knowing enough about that subject to tell the difference
between the experts and the cranks. Now he’s demonstrating, rather
embarrassingly, that he doesn’t know how to read CBO reports.

What I find amazing is the failure to learn the meta-lesson here,
which is not to wade into such matters without being quite sure you know
what you’re doing. In particular, if you think you’ve found a massively
important fact that somehow all the economists have missed — like a
drastic deterioration in CBO’s estimate of the long-run US budget
outlook, somehow missed by everyone else reading the agency’s reports —
you really, really want to be sure that you’re not just misreading the
numbers.